Polymerization of ethylene with alkali metal and group vi a metal oxide



United States Patent POLYMERIZATION OF ETHYLENE WITH ALKALI METAL ANDGROUP VI A METAL OXIDE Robert A. Mosher, Hammond, Ind., assignor toStandard Oil Company, Chicago, 111., a corporation of Indiana NoDrawing. Application January 14, 1954, Serial No. 404,130

14 Claims. (Cl. 260-943) This invention relates to improvements in thepolymerization of ethylene to form polymers of grease-like and/ornormally solid character, viz. polymers having a molecular weight of atleast about 300. More specifically, this invention relates to animprovement in processes for the polymerization of ethylene to polymershaving a molecular weight of at least about 300, said processes beingeifected by contact of ethylene with an alkali metal and a solidcatalytic material containing an oxide of a metal of group 6a (left-handsubgroup of group 6) of the Mendeleef Periodic Table, viz. one or moreof the oxides of chromium, molybdenum, tungsten or uranium. The basicprocess has been described and claimed in application for United StatesLetters Patent Serial No. 324,610 of Edmund Field and Morris Feller,filed December 6, 1952, now U. S. Patent 2,691,647, which isspecifically incorporated by reference herein.

In a continued study of the polymerization process of the aforesaidapplication, I have discovered that the rate of ethylene polymerizationcan be substantially increased by effecting said process in the presenceof an anhydrous hydrogen halide or a material capable of yieldinganhydrous hydrogen halide under the polymerization process conditions,as will be described in detail hereinafter.

One object of my invention is to provide a combination of novel andhighly useful catalysts for the preparation of high molecular weight,normally solid polymers from ethylene-containing gas mixtures. Anotherobject is to provide promoters which greatly increase the rate ofethylene polymerization in the presence of alkali metals and solidsubgroup 6a metal oxide catalysts. An additional object is to increasethe yields of solid ethylene polymers over those heretofore attained bythe use of alkali metal-subgroup 6a metal oxide catalysts. These andother objects of my invention will become apparent from the followingdescription and claims.

Briefly, the basic process, of which the present process is an inventiveimprovement, comprises the conversion of ethylene principally to highmolecular weight normally solid polymers by contact with an alkali metaland one or more of the oxides of chromium, molybdenum, tungsten oruranium, for example, a partially reduced molybdenum trioxide extendedupon a support. I may employ an activated alumina, titania or zirconiasupport and also a great variety of other supports for thepolymerization of ethylene to form normally solid polymers, e. g.,silica supports such as silica gel, kieselguhr, diatomite;silica-alumina, aluminosilicates, such as various clays and bleachingearths; and even adsorptive carbon, which is however not preferred. In apractical process, it is preferable to furnish a difficultly reduciblemetal oxide support for the group 6a metal oxide catalyst, e. g.gamma-alumina.

The alkali metals are lithium, sodium, potassium, rubidium and cesium,of which I prefer the first three because of their efiicacy, economy andrelative availability. While I prefer to employ the alkali metals assuch, I can employ various alloys or alloy-like compounds lice thereof,e. g., the various alkali metal silicides. The inventive process isefiected at temperatures between about C. and about 325 C., preferablybetween about C. and 260 C., and pressures between about atmospheric and15,000 p. s. i. g. or higher, preferably between about 200 and 5000, orabout 1000 p. s. i. g. The normally solid materials produced by thecatalytic conversion tend to accumulate upon and within the solidcatalyst.

It is desirable to supply to the reaction zone a liquid medium whichserves both as a reaction medium and a solvent for the solid reactionproducts. Suitable liquid reaction media for ethylene polymerizationinclude various hydrocarbons, particularly an'aromatic hydrocarbon suchas benzene, toluene or xylenes. However, the conversion ofethylene-containing gas streams can be eifected in the absence of aliquid reaction medium or solvent and the catalyst containingaccumulated solid polymeric conversion products can be treated from timeto time, within or outside the conversion zone, to effect removal ofconversion products therefrom and, if necessary, reactivation orregeneration of the catalyst for further use. I have discovered that theaddition of an anhydrous hydrogen halide into contact with ethylene andthe aforesaid catalysts comprising an alkali metal and a subgroup 6metal oxide exerts an unexpected and pronounced effect upon the rate ofethylene polymerization, sometimes causing the rate of ethyleneconversion to be doubled, as will be specifically illustrated in theexamples which follow. The anhydrous hydrogen halides which may beemployed are hydrogen fluoride, hydrogen chloride, hydrogen bromide andhydrogen iodide. Of these, I prefer to employ hydrogen chloride becauseof its general availability, economy and the relative ease with which itmay be handled in commercial operations. In lieu of the anhydroushydrogen halide I may employ a material which, under the conditionsobtaining in the polymerization reactor, yields substantially anhydroushydrogen halide, for example, an alkyl halide containing at least 2carbon atoms per molecule and cycloalkyl halides. Examples of alkylhalides are ethyl bromide, t-butyl chloride, amyl chlorides, propylfluoride, ethyl fluoride, dodecyl chloride and the like. Examples ofsuitable cycloalkyl halides are t-methylcyclopentyl chloride,t-methylcyclohexyl bromide, cyclohexyl chloride, cyclohexyl fluoride,t-ethylcyclopentyl iodide and the like.

I have made the further surprising discovery that anhydrous hydrogenhalide functions as a co-catalyst or promoter for the alkalimetal-subgroup 6a metal oxide catalyst combination only when it isemployed within a limited range of ratios relative to the alkali metal.The molar ratio of hydrogen halide to the alkali metal should be atleast sufficient to induce a substantial increase in the ethyleneconversion rate, usually at least about 0.1 mol of hydrogen halide pergram atom of said alkali metal and not substantially in excess of about1 mol of anhydrous hydrogen halide per gram atom of said alkali metal.When the amount of hydrogen halide employed in the polymerizationreaction substantially exceeds 1 mol per gram atom of alkali metal, thehydrogen halide functions as a poison for the catalyst rather than as apromoter, as will be brought out by specific data hereinafter supplied.The proportion of alkali metal employed can be varied from about 0.001to about 2 parts by weight per part by weight of the metal oxidecatalyst (total weight of solid catalyst). The promoting activity of themetals increases with increasing atomic weight. The optimum proportionscan readily be determined in specific instances, by simple small-scaletests with the specific feed stocks, liquid reaction medium, reactionmedium catalyst ratio, catalyst, temperature, pressure and nature of theproduct which is desired. Usually sodium is employed in pro- 3 portionsbetween about 0.01 and about 2 parts by weight or about 111m by weightper part by weight of molybdenum oxide containing-catalyst and ratiosbetween about 5 and -about 3000 volumes or more of liquid medium perpart by weight of metal oxide catalyst.

The relative proportions of support to the catalytic metal oxide may be:varied throughout a relatively wide range such that each component ispresent in amounts of at least approximately 1 weight percent. The usualmetal oxide-support ratios are in the range of about 1:20 to 11-1, orapproximately 1:10. I employ conditioned alumina-metal oxide catalystscomposed of gamma-alumina base containing about 1 to 80%, preferablyabout '5 to 35%, or approximately of catalytic metal oxide supportedthereon.

Gamma-alumina, titania and zirconia supports for my catalysts-may beprepared in any known manner and the oxides of molybdenum or other group6a metal may likewise be incorporated in,.or deposited on, the supportin any. known manner, e. g. as described in copending Serial No. 223,641(now U. S. Patent 2,692,257) of Alex Zletz and S'erial No. 223,643 (nowU. S. Patent 2,692,258) 'of Alan K. Roebuck and Alex Zletz, both filedon April 28, 1951. Excellent results may be obtained with molybdenaalumina, chromia-alumina and tungstia-alumina which can be catalysts ofthe type employed for effecting hydroforming, the word hydroformingbeing employed to mean processes of the type described in U. S. LettersPatent 2,320,147; 2,388,536; 2,357,332; etc.

The molybdena or other molybdenum-oxygen compound, such as cobaltmolybdate, may be incorporated in the catalyst base in any known manner,e. g. by impregnation, coprecipitation, co-gelling, and/or absorption,and the catalyst base and/ or finished catalyst may be heat-stabilizedin the known manners heretofore employed in the preparation ofhydroforming or hydrofining catalysts. Cobalt molybdate catalysts may beprepared as described in U. S. 2,393,288; 2,486,361; etc. Cobalt,calcium, nickel and copper salts of chromic, tungstic and uranic acidsmay also be employed with or without a support.

Although '"no partial reducing treatment of the metal oxide catalystsneed be effected when they are employed in the presence of alkali metal,a reducing or conditioning treatment ispreferred in commercialprocessing. The conditioning or reducing treatment of the hexavalentgroup 6a metal oxide is preferably eiiected with hydrogen although otherreducing agents such as carbon monoxide, mixtures of hydrogen and carbonmonoxide (water gas, synthesis gas, etc.), sulfur dioxide, hydrogensulfide, dehydrogenatable hydrocarbons, etc., may be employed. Hydrogencan be employed as a reducing agent at temperatures between about 350 C.and about 850 C., although it is more often employed attemperatureswithin the range of 450 C. to 650 C. The hydrogen partialpressure in the reduction or conditioning operation may be varied fromsubatmospheric pressures, for example even 0,1 pound (absolute) torelatively high pressures up to 3000 p. s. i. g., or even more. Thesimplest reducing operationsmay be effected with hydrogen at aboutatmospheric pressure,

The partial reduction of the metal oxide catalyst in which said metal ispresent in its hexavalent state can be effected in the presence of thealkali promoter, prior to contacting the combination of cataly ts withethylene. An induction period before ethylene polymerization can beeliminated or substantially reduced by pr ssur'ng hydrogen into thereactor containing the solvent, ethylene, metal oxide catalyst andalkali metal, e. g. at hydrogen pressuresbetween about 10 and about 900p. s. i. g., preferably 400-4001). s. i. g.; under these conditions asmall 6a metal trioxide -is carried out to the extent that theaverage'valence state of the catalytie metal in the catalyst lies withinthe range of about 5.5 to about 2, preferably between about 3.0 andabout 5.0.

The catalysts can be employed in various forms and sizes, e. g., aspowder, granules, microspheres, broken filter cake, lumps, or shapedpellets. A convenient form in which the catalysts may be employed is asgranules of about 20-100 mesh/ inch size range.

The charging stock to the present polymerization process preferablycomprises essentially ethylene. The ethylene charging stocks may containhydrogen and hydrocarbons, as in refinery gas streams, for example, mathane, ethane, propane, etc. However, it is preferred to employ as pureand concentrated ethylene charging stocks as it is possible to obtain.When the charging stock contains propylene as well as ethylene, boththese olefins may contribute to the production of resinous, highmolecular weight products.

it is desirable to minimize or avoid the introduction of oxygen, carbondioxide, water or sulfu'rcomp'oiinds into contact with the catalyst. f

In general, polymerization can be effected in thep'resent process attemperatures between about C. and about 325 C. Usually polymerization iseffected in the present process at temperatures between about C. andabout 275 C. for the preferred narrower range of about 220 to about 260C. The conjoint use of polymerization temperatures between about 230 andabout 260 C. and a liquid hydrocarbon reaction mediu'm'such as benzene,xylenes, decalin or methyl decalins is highly desirable in producingethylene polymers having viscosities (X10?) ranging on the average fromabout 10,000 to about 30,000 in continuous operations with relativelylong on-stream periods and 'active catalysts.

It has been found that the present process can be employed for'theproduction of relatively high molecular weight ethylene polymers atrelatively low'press'ur'es. The process of the present invention can beefiected to some extent even at atmospheric pressure. The upper limit orthe partial pressure of ethylene in the process is dictated by economicconsiderations and equipment limitations and may be 10,000 p. s. i. g.,20,000 p. s. i. g.,or even more. A generally useful and economicallyd'es'ir'abl'e ethylene pressure range is between about 200 and about 500p. s. i. g., preferably between'about 500 and about 3500 p. s. i. g.,about 1000 p. s. i. g.

The contact time or 'space velocity employed in the polymerizationprocess will be selected with reference to the other process variables,catalysts, 'th'e'specific type of product desired and the extent ofethylene conversion desired in any given run or passover the catalyst.In general, this variable is readily adjustable 'to obtain the desiredresults. In operations in which the ethylene charging stock is caused toflow continuously into and out of contact with the solid catalyst,suitable liquid hourly space velocities are usually between about 0.1and about 10 volumes, preferably about0j5 to "5 or about 2 volumes ofethylene solution in 'a liquid reaction medium, which is usually anaromatic hydrocarbon su'cha's benzene, xylenes or tetralin, or acycloalip'hatic hydrocarbon, such as decalin '(decahydronaphthal'enfi.The amount of ethylene in such solution may be in the range of about 2to 50% by weight, prefera'bly about 2 to about 10 Weight per cent or,for example, about '5 to 10 weight percent.

an alkali-metal in the reaction zone, is very important in obtaininghigh yields of polymer.

Ethylene can be polymerized in the gas phase and in the absence of aliquid reaction medium by contact with anhydrous hydrogen halide, alkalimetal and group 6a metal oxide catalysts. Upon completion of the desiredpolymerization reaction it is then possible to treat the solid catalystfor the recovery of the solid polymerization products, for example byextraction with suitable solvents. However, in the interests ofobtaining increased rates of ethylene conversion and of continuouslyremoving solid conversion products from the catalyst, it is desirable toeffect the conversion of ethylene in the presence of suitable liquidreaction media. The liquid reaction medium may also be employed as ameans of contacting the ethylene with catalyst by preparing a solutionof ethylene in the liquid reaction medium and contacting the resultantsolution with the polymerization catalyst. Anhydrous hydrogen halide maybe absorbed in the liquid reaction medium under pressure and beintroduced as a hydrocarbon solution into the reaction zone. The liquidreaction medium functions as a solvent to remove some of the normallysolid product from the catalyst surface.

Various classes of hydrocarbons or their mixtures which are liquid andsubstantially inert under the polymerization reaction conditions of thepresent process can be employed. Members of the aromatic hydrocarbonseries, particularly the mononuclear aromatic hydrocarbons, viz.,benzene, toluene, xylenes, mesitylene and xylene-p-cymene mixtures canbe employed. Tetrahydronaphthalene can also be employed. In addition, Imay employ such aromatic hydrocarbons as ethylbenzene, isopropylbenzene,n-propylbenzene, sec-butylbenzene, t-butylbenzene, ethyltoluenes,ethylxylenes, hemimellitene, pseudocumene, prehnitene, isodurene,diethylbenzenes, isoamylbenzene and the like. Suitable aromatichydrocarbon frictions can be obtained by the selective extraction ofaromatic naphthas, from hydroforming operations as distillates orbottoms, from cycle stock fractions of cracking operations, etc.

I may also employ certain alkyl naphthalenes which are liquid under thepolymerization reaction conditions, for. example, l-methylnaphthalene,2-isopropylnaphthalene, l-n-amylnaphthalene and the like, orcommercially produced fractions containing these hydrocarbons.

Certain classes of aliphatic hydrocarbons can also be employed as aliquid hydrocarbon reaction medium in the present process. Thus, I mayemploy various saturated hydrocarbons (alkanes and cycloalkanes) whichare liquid under the reaction conditions. Either pure alkanes orcycloalkanes, or commercially available mixtures, freed of catalystpoisons, may be employed. For example, I may employ straight runnaphthas or kerosenes containing alkanes and cycloalkanes. Specifically,I may employ liquid or liquefied alkanes such as n-pentane, nhexane,2,3-dimethylbutane, n-octane, iso-octane (2,2,4- trimethylpentane),n-decane, n-dodeeane, cyclohexane, methylcyclohexane,dimethylcyclopentane, ethylcyclohexane, decalin, methyldecalins,dimethyldecalins and the like.

I may also employ a liquid hydrocarbon reaction medium comprising liquidolefins, e. g., n-hexenes, cyclohexene, l-octene, hexadecenes and thelike.

The normally solid polymerization products which are retained on thecatalyst surface or grease-like ethylene polymers may themselvesfunction to some extent as a liquefied hydrocarbon reaction medium, butit is highly desirable to add a viscosity-reducing hydrocarbon, such asthose mentioned above. thereto in the reaction zone.

The liquid hydrocarbon reaction medium should be freed of poisons byacid treatment, e. g., with anhydrous p-toluenesulfonic acid, sulfuricacid, or by equivalent treatments, for example with aluminum halides orother Friedel-Crafts catalysts, maleic anhydride, calcium, calciumhydride, sodium or other alkali metals, alkali metal hydrides, lithiumaluminum hydride, hydrogen and hydrogenation catalysts (hydrofining),filtration through a column of copper grains or 8th group metal, etc.,or by combinations of such treatments.

I have purified C. P. xylenes by refluxing with a mixture of MoO3Al203catalyst and LiAlH'i (50 cc. xylene- 1 g. catalyst0.2 g. LiAlHi) atatmospheric pressure, followed by distillation of the xylenes. Stillmore effective purification of solvent can be achieved by heating it toabout 225-250 C. with either sodium and hydrogen or NaH in'a pressurevessel.

Temperature control during the course of the ethylene conversion processcan be readily accomplished owing to the presence in the reaction zoneof a large liquid mass having relatively high heat capacity. The liquidhydrocarbon reaction medium can be cooled by heat exchange inside oroutside the reaction'zone. It should be noted, however, that in someinstances the solvent may be present as a dense gas phase.

In order specifically to illustrate the present invention withoutthereby unduly limiting the same, the following examples are presented.In the examples, a ml. stainless steel autoclave was employed, providedwith a mag netically-actuated stirrup-type stirrer which wasreciprocated through the reaction mixture. In each instance theautoclave was charged with 50 ml. of freshly distilled benzene, whichwas substantially free of oxygen, water and carbon dioxide. The reactorwas also charged, except asotherwise indicated, with 0.5 g. of acommercial hydroforming catalyst which was 8 weight percent M003supported upon gamma-alumina, prereduced before use by treatment with astream of dry hydrogen at atmospheric pressure for about 16 hours at 450C. The reactor was in each instance charged with the desired amount ofalkali metal. All charging operations were carried out under an inertgas blanket. The reactor contents were heated with stirring to 230 C.and ethylene was then pressured into the reactor to an initial value ofabout 1000 p. s. i. The hydrogen halide was then introduced and the rateof reaction was measured by noting the ethylene pressure drop duringvarious periods of reaction. In Example 2, in which amyl chloride wasemployed as a promoter, it was charged with. the benzene reactionmedium.

Example 1 In this operation 6.95 mg. atoms (gram atoms times 1000) ofsodium were employed, together with 1.64 millimols of anhydrous hydrogenchloride. It was found that the rate of ethylene absorption during thefirst hour was 880 p. s. i, and during the first 4 hours it totaled 2050p. s. i. Physical difiiculties were encountered in effecting thisreaction because the rate of formation of solid ethylene polymer was sogreat that at the end of the first 3 hours of reaction it became almostimpossible to continue operation of the magnetic stirring mechanism, sothat thereafter very poor contacting was obtained. Nevertheless,reaction was continued for a total period of 12 hours to yield 19.8 g.of a tough, normally solid, ethylene polymer per gram of the hydroformercatalyst. The melt viscosity of the polymer (method of Dienes and Klemm,J. Appl. Phys. 17, 458-71 (1946)) was 26x10. In a control run wherein10.42 mg. atoms of sodium were employed under the same conditions but inthe absence of hydrogen chloride, it was found that the ethyleneconversion during the first hour of reaction corresponded only to apartial pressure drop of 580 p. s. i. and at the end of 4 hours, to 1050ps i. Stirrer jamming was not encountered until late in the reactionperiod. Reaction was continued for 16 hours to yield 14.8 g. of tough,normally solid, ethylene polymer per gram of hydroformer catalyst, saidpolymer having a melt viscosity of 1.3 x10".

The following data show that the use of substantially more than one molof-HCl per gram atom of sodium poisoned the catalyst. In this instance10 millimols of anhydrous HCl were employed with 6.95 mg. atoms ofsodium under otherwise constant conditions, compared with the aboveexample. It was found that the ethylene pressure drop during the firsthour of reaction was only 220 p. s. i. and at the end of 3.5 hours, wasonly 820 p. s. i. Reaction was continued for 15.5 hours to yield 9.8 g.of normally solid ethylene polymer per gram of hydrofor'ming catalyst,which is a substantially lower yield than was obtained without the useof HCl. Moreover, the melt viscosity of the polymer obtained in thisoperation was 8.6X10 which is substantially lower than those obtained inthe operations described above; this shows that excess HCl lowered themolecular weight of the ethylene polymer.

. Example 2 'In this operation 0.94 millimol of n-amyl chloride wasemployed together with 10.4 mg. atoms of sodium. The partial pressure ofethylene during the first hour of "reaction dropped 700 p. s. i. and in3.75 hours, it dropped 1630 p. s. i. Here again, relatively poorcontacting was obtained in the reaction zone due to the rapidaccumulation ofsolid ethylene polymer, but contacting could obviously beimproved by the employment of properly designed equipment. The reactionyielded 14.8 g. of tough, normally solid ethylene polymer per gram ofhydroformer catalyst 'over a total reaction period of 12 hours. The meltviscosity of the ethylene polymer was 2.1x 10 Example 3 The process ofExample 1 is repeated but anhydrous hydrogen bromide is substituted inequimolar proportion for the hydrogen chloride employed in Example 1.

Example 4 The process of Example 1 is repeated but liquid 'anhydroushydrogen fluoride is introduced into the reactor with benzene in anamount equimolar with the amount of hydrogen chloride in Example 1.

Example 5 The process or Example 1 is carried out, but weight percent(X203 supported 'upon gamma-alumina is employed in the place of themolybden'a-alumina catalyst of Example 1. The chromia-alumina catalystis prereduced before use by the technique employed for the prereductionof the molybdena-alumina catalyst.

Example 6 The process oi -Example 2 is repeated but the metal-oxidecatalyst is 5 weight percent W03 supported upon a silica gel,.prereduced before use by the technique employed foryprereduction ofmolybdena-gamma-alumina catalysts.

Example 7 In this operation l employed 23 milligram atoms ofmetalliclithium and 1.7 millimols of hydrogen chloride. The

ethylene pressure drop in 4 hours was 310 p. s. i. The run wascontinued-for hours and 4.4 grams per gram of catalyst of a normallysolid ethylene polymer was obtained.

Example 8 :rnerizable materials and particularly with propylene.Other-.polymerizable materials include mono-olefinic hy 'drocarbons suchas n-butylenes, isobutylene, 't-butylethylene and the like, usually inproportions between about 1 and about 25% by weight, based on the weightof ethylene.

In large scale operations, the continuous process described inconnection with the figure of Serial No. 324,610 may be employed,modified by the addition of means for introducing anhydrous hydrogenhalide into the reactor and of separating traces of hydrogen halidewhich may be present in the product reaction mixture by conventionalmeans, such as the addition of ammonia or other alkalies, etc. 7

I may employ group 5a metal oxide catalysts in lieu of, or in additionto, the group 6a metal oxides in my process, viz., oxides of vanadium,columbium and tantalum, the process remaining otherwise unchanged in allessential regards.

The practice of the process of the present invention leads to ethylenepolymers of widely variant molecular weight ranges and attendantphysical and mechanical properties, dependent upon the selection ofoperating conditions. The inventive process is characterized by extremeflexibility both as regards operating conditions and as regards theproducts producible thereby. Thus the present process can be effectedover extremely broad ranges of temperature and pressure. The practice ofthe present process can lead to grease-like ethylene polymers having anapproximate molecular weight range of 300 to 700, wax-like ethylenepolymers having an approximate specific viscosity.( 10 between about1000 and 10,000, and tough, resinous ethylene polymers having anapproximate specific viscosity (X10 of 10,000 or more than 300,000 [(1relative 1) 10 The polymers produced by the process of this inventioncan be subjected to such after-treatment as may be desired, to fit themfor particular uses or to impart desired properties. Thus, the polymers'can'be extruded, mechanically milled, filmed or cast, or converted tosponges or latices. Antioxidants, stabilizers, fillers, extenders,plasticizers, pigments, insecticides, fungicides, etc. can beincorporated in the polyethylenes and/or in by-product alkylates orgreases. The polyethylenes may be employed as coating materials,binders, etc. to an even wider extent than polyethylenes made by priorprocesses.

The polymers produced by the process of the present invention,especially the polymers having high specific viseosities, can be blendedwith the lower molecular Weight polyethylenes to impart stiffness orflexibility or other desired properties thereto. The solid resinousproducts produced by the process of thepresent invention can, likewise,be blended in any desired proportions with hydrocarbon oils, waxes suchas parafiin or petrolatum waxes, with ester waxes, with high molecularweight polybutylenes, and with other organic materials. Smallproportions between about 0.-0l and about 1 percent of the variouspolymers of ethylene produced by the process of the present inventioncan be dissolved or dispersed in bydrocarbon lubricating oils toincrease V. I. and to decrease oil consumption when the compounded oilsare employed in motors; larger amounts of polyethylenes may becompounded with oils of various kinds and for various purposes.

The products having a molecular weight of 50,000 or more produced by thepresent invention, can be employed in small proportions to substantiallyincrease the viscosity of fluent liquid hydrocarbon oils and as gellingagents for such oils.

The polymers produced by the present process can be subjected tochemical modifying treatments, 'such as halogenation, halogenationfollowed by dehalogenatiomsulfohalogenation,e. g., by-treatment'withsulfuryl chlorideor a mixture of S02 1 and I C12, 'sulfonation, andother reactions to which hydrocarbons may be subjected.

Havingthus described my invention, whatI claim isz I. In a process forthe productionof an ethylene polymer having a molecular weight greaterthan about 300 which comprises contacting ethylene with an alkali metaland an oxide of a metal of group 6a of the Mendeleef Periodic Table at areaction temperature between about 75 C. and about 325 C., theimprovement which comprises effecting said contacting in the presence ofan anhydrous hydrogen halide in a molar concentration not in excess ofsaid alkali metal but sufficient substantially. to increase the rate ofethylene polymerization.

2. In a process for the production of an ethylene polymer having amolecular weight greater than about 300 which comprises contactingethylene with an alkali metal and an oxide of a metal of group 6a of theMendeleef Periodic Table at a reaction temperature between about 75 C.and about 325 C., the improvement which comprises effecting saidcontacting in the presence of an anhydrous hydrogen halide in an amountbetween about 0.1 p

and about 1 mol per gram atom of said alkali metal.

3. The process of claim 2 wherein said oxide is partially prereducedbefore use.

4. The process of claim 3 wherein said hydrogen halide is hydrogenchloride.

5. In a process for the production of an ethylene polymer having amolecular weight greater than about 300 which comprises contactingethylene with an alkali metal and an oxide of a metal of group 6a of theMendeleef Periodic Table in the presence of a liquid hydrocarbonreaction medium at a reaction temperature between about 75 C. and about325 C., the improvement which comprises etfecting said contacting in thepresence of an anhydrous hydrogen halide in an amount between about 0.1and about 1 mol per gram atom of said alkali metal.

6. In a process for the production of a normally solid hydrocarbonmaterial which comprises the steps of contacting ethylene and a liquidhydrocarbon reaction medium with an alkali metal and a minor proportionof an oxide of molybdenum supported upon a major proportion 10 of adiflicultly reducible metal oxide at a reaction temperature betweenabout 75 C. and about 325 C., the improvement which comprises effectingsaid contacting in the presence of an anhydrous hydrogen halide in anamount between about 0.1 and about 1 mol per gram atom of said alkalimetal.

7. The process of claim 6 wherein said alkali metal is sodium and saidhydrogen halide is hydrogen chloride.

8. The process of claim 6 wherein said alkali metal is lithium and saidhydrogen halide is hydrogen chloride.

9. The process of claim 6 wherein said alkali metal is potassium andsaid hydrogen halide is hydrogen chloride.

10. The process of claim 6 wherein said hydrogen halide is generatedwithin the reaction zone by decomposition under the reaction conditionsof an alkyl halide hav ing at least two carbon atoms in the molecule.

11. The process of claim 10 wherein said alkyl halide is achloropentane.

12. In a process for the production of a normally solid hydrocarbonmaterial which comprises the steps of contacting ethylene and a liquidmonocyclic aromatic hydrocarbon reaction medium with sodium and a minorproportion of an oxide ofmolybdenum supported upon a major proportion ofan activated alumina, the weight ratio of sodium to oxide catalyst beingbetween about 0.001 and about 2, at a reaction temperature between about75 C. and about 325 C., the improvement which comprises effecting saidcontacting in the presence of anhydrous hydrogen chloride in an amountbetween about 0.01 and about 1 mol per gram atom of said sodium.

13. The process of claim 12 wherein said reaction temperature is betweenabout 220 C. and about 260 C.

14. The process of claim 12 wherein the weight ratio 4 of sodium tooxide catalyst is between about 0.01 and

1. IN A PROCESS FOR THE PRODUCTION OF AN ETHYLENE POLYMER HAVING AMOLECULAR WEIGHT GREATER THAN ABOUT 300 WHICH COMPRISES CONTACTINGETHYLENE WITH AN ALKALI METAL AND AN OXIDE OF A METAL OF GROUP 6A OF THEMENDELEEF PERIODIC TABLE AT A REACTION TEMPERATURE BETWEEN ABOUT 75* C.AND ABOUT 325* C., THE IMPROVEMENT WHICH COMPRISES EFFECTING SAIDCONTACTING IN THE PRESENCE OF AN ANHYDROUS HYDROGEN HALIDE IN A MOLARCONCENTRATION NOT IN EXCESS OF SAID ALKALI METAL BUT SUFFICIENTSUBSTANTIALLY TO INCREASE THE RATE OF ETHYLENE POLYMERIZATION.